10. Common Stock

The Company had reserved shares of common stock, on an as-converted basis, for future issuance as follows:

	December 31,
	2016		2015
Options issued and outstanding		10,690,156		9,931,229
Shares available for future stock option grants		5,011,459		4,810,271
Common stock warrants		97,621		929,437
Total		15,799,236		15,670,937

Initial Public Offering and Concurrent Private Placement

On April 20, 2015, the Company closed its initial public offering, or IPO, and sold 8,050,000 shares of its common stock (inclusive of 1,050,000 shares of common stock pursuant to the full exercise of the underwriters’ option to purchase additional shares) at a price to the public of $17.00 per share. The Company received aggregate net proceeds of $124.2 million, net of underwriting discounts and offering expenses. The Company also sold to Novartis Institutes for BioMedical Research, Inc., or NIBR, in a concurrent private placement 1,470,588 shares of common stock at a price of $17.00 per share for proceeds of $25.0 million. Upon the closing of the IPO, all then-outstanding shares of convertible preferred stock converted by their terms into 51,822,659 shares of common stock. Additionally, the Company amended and restated its certificate of incorporation effective April 20, 2015 to, among other things, change the authorized number of shares of common stock to 300,000,000 shares and the authorized number of shares of preferred stock to 10,000,000 shares.

At-the-Market Sales Agreement

In May 2016, the Company entered into an “at-the-market” sales agreement, or the Sales Agreement, with Cowen and Company, LLC, or Cowen, through which the Company may offer and sell shares of its common stock having an aggregate offering of up to $100.0 million from time to time through Cowen, acting as the Company’s sales agent. The issuance and sale of these shares by the Company pursuant to the Sales Agreement are deemed an “at-the-market” offering under the Securities Act of 1933, as amended. Under the Sales Agreement, the Company has agreed to pay Cowen a commission of up to 3% of the gross proceeds of any sales made pursuant to the Sales Agreement. During 2016, the Company received net proceeds of $36.8 million, after deducting commissions and expenses payable by the Company, from the sale of 2,526,229 shares of common stock pursuant to the Sales Agreement. As of December 31, 2016, the Company had an aggregate of $63.2 million available to be offered under the Sales Agreement, subject to the continued effectiveness of its current shelf registration statement or an effective replacement shelf registration statement.